Con Coughlin is the Telegraph's Defence Editor and a world-renowned expert on global security and terrorism issues. He is the author of several critically acclaimed books. His new book, Churchill's First War: Young Winston and the fight against the Taliban, is published by Macmillan in London and Thomas Dunne Books in New York. He appears regularly on radio and television in Britain and America.

Britain's war cemetery in Kabul is a sobering reminder of our sacrifice in Afghanistan

I have just spent a very sobering morning visiting the British military cemetery in Kabul which is dedicated to all those who have made the ultimate sacrifice in more than two centuries of conflict in Afghanistan.

At the southern end of the cemetery are the remnants of just ten of the headstones that marked the graves of the 150 British soldiers who died in Kabul fighting in Britain's two ill-fated campaigns to Afghanistan in the nineteenth century. The original graves had been desecrated by the Afghans after the British made their last withdrawal from Kabul in 1882. When British forces returned to Kabul in 2001 following the overthrow of the Taliban they managed to recover the remnants of some of the headstones, which have now been restored and set into a wall commemorating our nineteenth century war dead.

Of more significance for us today, though, is the shiny new memorial that has been set up next to it for all the members of British Armed Forces who have lost their lives in the modern conflict. More than 400 British service personnel have now lost their lives since those first heady days when we stormed into Kabul in 2001 under the mistaken belief that, by overthrowing the Taliban government and routing their al-Qaeda allies, our mission to Afghanistan had been accomplished.

How wrong we were. The names listed on the Kabul memorial, together with their regiments or service, tell the painful tale of Britain's problematic involvement in Afghanistan, particularly since British forces deployed to southern Afghanistan in the summer of 2006 in support of Nato's mission to support the Afghan government's reconstruction effort. They include the names of the RAF crew who were killed when their Nimrod reconnaissance aircraft exploded in mid-air while refuelling in September 2006. It contains the names of all those who lost their lives in the brutal summer of 2009 in the bloody battle for Sangin, while the more recent victims lost their lives during the successful attempt to drive the Taliban from their strongholds in southern Helmand.

Looking at the names on the memorial it is tempting to think what a terrible waste of life, particularly when you consider that the efforts of all those who perished fighting in Afghanistan in the nineteenth century ultimately achieved very little.

And that could easily happen again if the major world powers fail to provide the necessary safeguards for Afghanistan once the current round of combat operations are concluded in 2014, and British forces return home. As Sir William Patey, the outgoing British Ambassador to Kabul, remarks in his interview with me in today's Daily Telegraph, if such support is not forthcoming at the Nato conference in Chicago in May, we might as well pack up and go home now.

A great deal of progress has been made in Afghanistan in recent years, mainly due to the recent military "surge" strategy which has inflicted serious damage on the Taliban. But the mission to restore Afghanistan to something approaching a stable state is far from over, and if we do not continue to support the country post-2014 it could easily return to its former lawless state.

And for all those who harbour doubts about our future commitment to this benighted country, I strongly recommend they pay a visit to the Kabul war cemetery where they might start to understand the true meaning of sacrifice.